In known cast iron boilers, typically utilized in residential or commercial settings to provide heated water for heating purposes or the like, the inhibition of a boiling action in the boiler fluid is paramount. As will be appreciated, boiling of the boiler fluid causes a substantial, and frequently rapid, expansion of the boiler fluid volume, which may precipitate possible catastrophic damage to the system as a whole. Thus, differing boiler configurations have been employed to prevent the occurrence of actual boiling in the boiler system.
One commonly employed method utilized to prevent boiling in boiler systems is the introduction of increased pressure within the boiler chamber and related piping. By increasing the pressure within the system, it is possible to heat the boiler fluid to a temperature above what its normal boiling point would be at ambient atmospheric pressure. Increased boiler chamber pressure thus enables the production of superheated boiler fluid, which may then be effectively utilized throughout the heating system while avoiding any damaging volumetric expansion of the boiler fluid.
Another known method of limiting the conditions conducive to boiling involves causing the boiler fluid to circulate, or flow, in a manner that will effectively disperse the heat in the boiler equally to all portions of the boiler fluid. The management of boiler fluid flow paths and velocity are integral to both below-fired boilers and down-fired boilers.
In below-fired boilers, the burner assembly is typically located adjacent the bottom of the boiler, thereby causing rapid mixing and circulation of the boiler fluid due to buoyant convection in the total liquid volume. Fluctuations in the return water temperature, BTU input or saturation temperature are thereby absorbed in the total heat capacity of the boiler.
In down-fired boiler configurations, the burner assembly is instead located adjacent the upper portion of the boiler, effectively having no volume of water above the area where heat is being generated. Consequently, the heat being added to the system is dispersed and circulated via convection. In an effort to increase the circulation and efficiency of down-fired boilers, a series of inner baffles are known to be utilized within the boiler chamber to create a measure of fluid velocity across the inner surface of the boiler chamber.
The use of baffles, while increasing somewhat the velocity and circulation of the boiler fluid, presents its own set of concerns. The sheer number and configuration of the inner baffles increase the difficulty, and related costs, of the casting process when manufacturing typical cast iron boilers. Moreover, the inner baffles themselves may create pockets of non-circulating, or low-circulating, fluid. This is true particularly in the areas adjacent where the baffles contact the side walls of the boiler chamber. As known to those of skill in the art, localized areas of low or non-circulating boiler fluid creates an environment that may promote undesirable boiling. There thus exists a need to design a down-fired boiler that not only promotes boiler fluid circulation, but also reduces the incidence of low-circulating pockets of fluid.
Another concern for down-fired boilers is the operation of the burner assembly itself. In such systems, the fuel mixture is typically dispersed across the entire surface of the burner element at essentially the same time. Since the initial ignition of the fuel mixture occurs at one location adjacent the burner element, the fuel mixture located away from the ignition site typically propagates some distance away from the burner element prior to igniting.
As will be appreciated, the ignition of pockets of fuel located some distance away from the burner element causes a rough and oftentimes noisy ignition that, over time, may cause damage to the burner element as well as being audibly disconcerting.
With the forgoing problems and concerns in mind, it is the general object of the present invention to provide a down-fired boiler and burner apparatus that reduces the sensibility to boiling as well as increases the efficiency of the burner assembly.